The subject matter disclosed herein relates to turbomachines and, more particularly, to an inlet heating system for a gas turbine.
In some gas turbine applications, there are instances of gas turbine plant operation where gas turbine pressure ratio reaches an operating pressure ratio limit of the compressor causing compressor surge. The compressor pressure ratio is typically larger than the turbine pressure ratio in that the latter is subject to pressure loss in the combustor. In order to provide compressor pressure ratio protection, compressor discharge air is bled off and re-circulated to the compressor inlet. This method of operation, known as inlet bleed heat (IBH) control, raises inlet temperature of the compressor inlet by mixing colder ambient air with the bleed portion of the hot compressor discharge air.
Conventionally, in order to maintain compressor inlet temperatures within a small range, a large number of vertical manifolds are arranged between the bleed air and the compressor inlet. While the vertical manifolds provide mixing in the horizontal plane, temperature gradients remain within the bleed air making it difficult to maintain the compressor inlet temperature within the small range.